OH wow. I would be PISSED if I thought my girls were ever sedated.
We've had pretty a bad experience too. Back in Sugar Land Tx where I just moved from.... I had taken Chanel to a referred Groomer ....
Her 1st visit went ok - but the 2nd time - She was whimpering on the way home when I touched her side

. I was fuming at the groomer. I KNOW she hurt her.

Chanel is an ANGEL at the vets & groomer so I know she didn't do anything to warrant being treated rough.
I am normally easy going but hearing her cry turned me into MomZilla.
I called them right away and spoke to her boss - and Chanel was never the same in the car after that - every time we went 'bye bye's' which normally had her jumping with joy - she'd be in the car whimpering and kissing me as I drove - she HATED going for rides.
It took me 6 months of little car rides to nowhere to get her to forget her experience and I really hope that woman got in trouble.
NO DOG SHOULD LEAVE A GROOMER Sedated or crying.
and IF I EVER Saw that groomer again - I would still say something to her. I should have gone back there and made a scene in front of her customers - I wanted to but that just isn't my style.